Container and method of making same



F. GILBERT, .JR

CONTAINER AND METHOD oF MAKING SAME Filed May 4, 1942 INVENTOIR FRANK GILBERT, Je.

El? el.

ATTORNEYS Patented Sept. 17, 1946 AUNITED STATES PATENT OFFICE CONTAINER AND METHOD OF MAKING SAME Frank Gilbert, Jr., Olmsted Falls, Ohio Application May 4, 1942, Serial No. 441,649

s claims. (C1. .9s-s6) This invention relates to animprovement in containers and methods of making said containers. More particularly, this invention relates to a method of rendering containers of fibrous sheet material exceptionally rigid, liquid-proof and impervious to most common gases and vapors.

Heretofore, containers of `brous materials, such as paperboard, chipboard, strawboard, or like paper stocks, generally have not been satisfactory for packaging heavy materials or materials which are likely to lose or absorb moisture. In the first place, such containers seldom possessed suicient rigidity unless the wall thicknesses were increased to unwieldy proportions.`

a rigidity and strength approaching that of the` well-known metal and glass containers.

Another object of this invention is to provide a brous container and a method of sealing which will permit a vacuum to be created and maintained within the container.

It is also an object of this invention to provide a double-wall container having a hermetically sealed space between the walls of the container.

Other and further objects and advantages of this invention will be apparent from the following speciiication, claims, and drawing, in which:

Fig. 1 is a cross-section of an outer shell and an elevation of an inner shell showing a manner of assembling acontainer made according to my invention.

Fig. 2 is a cross-section taken along the line 2 2 of Fig. 1 showing one form of an assembled container made according to my invention.

Fig. 3 is a view similar to Fig. 2 showing another form of an assembled container made according to my invention.

In the drawing, in which like reference characters refer to like parts,` I represents an outer shell or container comprised of a spirally wound tube Il having one end spun in to provide anY vinner flange I2 on which a diskV I3 is seated to provide a bottom closure for the tube II. The tube I I is closed with a top cap I4 similar :in construction to the bottom closure of the tube II. 20 represents an inner shell or container comprised of a spirally Wound tube 2| closed at one end with a bottom closure cap 23 of stamped paper and at the other end `Witha top closure cap 24 of stamped paper. The bottom cap 23 is provided with a suitable spacer 25 and the tube 2| is likewise provided with suitable centering spacers 26. The outer shell I0 and the inner shell 2u are both preferably comprised entirely of brous sheet material, such as heavy kraft paper, chipboard, paperboard, strawboard, or like paper stock. The outer surfaces of the outer shell Ill may be suitably glazed or lacquered and may carry any desired printing or label. The inner surface of the tube 2I and cap 23 may also be suitably glazed or coated, if desired. As will be apparent from the following, it is preferable that the inner surface of the outer shell I0 and the outer surface of the inner shell 20 should be unglazed or, at the most, only slightly glazed or nished in order to allow the shells to be impregnated with the filler. Also, it is preferable that the top cap 24 be made of porous stock carrying only a small amount, if any, of sizing or iiller which tends to render the stock non-porous.

The closures for the outer shell II) are shown as being of the well-known spun tube and disk construction and the closures for the inner shell 2|]l are shown to be stamped paper caps, in order to illustrate twotypes of closures, each of which may be used for both shells. Obviously, other types of end-closures may be used for the shells where such other types of closures would be convenient and practical.

The several spacers 25 and 26 are preferably embossed or deeply scored projections on the inner shell 20. Such spacers, however, may also be made by attaching strips or spots of paper stock, or non-porous material, such as sealing wax, to the outer surfaces of the inner shell 20. It is also apparent that the same function of centering and spacing the inner shell Z in the outer shell III would be served by similar spacers on the inner surface of the outer shell I0.

A preferred manner of assembling my container is shown in Fig. 1. The open outer shell I0 is partly lled with a molten filler 3U which is substantially solid at normal atmospheric temperatures. 'Ihe closed inner shell 20, lled with the substance to be packaged, 40, is then inserted in the outer sneu Io while the nner sa is stm in a nuid condition. As the inner shell 20 is placed within the cuter shell so that it is centered in the outer shell by the spacers 26 and spaced from the bottom I3 by the spacer 25, the molten ller is extruded up between the walls of the inner and outer shells, completely filling the space therebetween up to the level attained due to its displacement by the shell 20. The filler 30 is then allowed to solidify. The cap I4 may be placed on the open end of the shell IIJ either after or before the filler solidifies, depending upon whether a completely filled container, as shown in Fig. 2, or a hollow wall container, as shown in Fig. 3, is desired.

The ller 3D is preferably a wax, such as paraffin, and/or a resin, such as pine rosin, which will not only solidify into a rigid mass at atmospheric temperature but which will also penetrate and impregnate the walls of the inner and outer shells.

A mixture of paramn wax and rosin is often pref` erable for the filler 30, since the mixture of the two cheap constituents of such a filler is less brittle than either of the constituents alone. It is obvious, however, that one may use any other suitable and normally solid filler, plasticized 'if necessary, which is substantially impervious to the gases, vapors, or Aliquid which it is desired either to retain in th packaged contents 40 or from which the packaged contents are to be protected. A mixture of paraffin wax vand pinerosin is usually a satisfactory filler when it is desired to have the package impervious to air, water and water-vapor, and 'many petroleum products. How my container prevents leakage of petroleum products which normally seep or wick through vessels consisting only of paper stock or only of the filler is not understood.

By employing a top cap 24 which is of porous stock, I achieve a vacuum packaging of the contents 40. When the closed inner shell 20 is inserted into the outer shell I partly filled with the hot molten filler 30, the contents 40 are heated and expanded, expelling air and other gases within the shell 2li through the porosities of the inner shell 20, and, particularly, through the porosities of the cap 24. As the filler 3B, which surrounds the inner shell 20, cools and solidifies, however, the porosities in the shell 2Il are filled and impregnated by the solidifying filler. Consequently, air does not return into the inner shell as the contents of the inner shell (including residual gases, if any) cool and tend to contract. Thus, the inner shell is thoroughly sealed and I at least apartial vacuum is created and maintained within the inner shell.

It is often preferable and advantageous to have the inner shell and contents 40 heated when the inner shell is immersed in the molten filler 30. The advantages generally obtained are: first, freezing or solidication of the filler is delayed, thereby preventing the formation of voids which extend across the space between lthe shells and cause portions of the walls of the shells to be uncoated or unimpregnated by the filler; second, impregnation of the inner surface of the outer shell and of the outer surface of the inner shell is assisted; third, the vacuum within the inner shell tends to be increased.

In the container illustrated in Fig. 2, the filler 30 completely fills the space between the inner and outer shells. This construction is obtained by placing in the open shell I0 a volume of molten filler approximately equal to the total volume of space between the shells and the volume of filler impregnated in the shells. If Vthe inner shell tends jto float in the moltenf'iller, pressure should be applied to maintain the spacer 25 in contact with the bottom I3 until the filler solidiies suiciently to prevent the inner shell from floating. If the filler tends to shrink when cooling, a sufficient amount of filler should vthen be added to fill the outer shell before closing it with the cap I4.

The container illustrated in Fig. 3 is provided with a substantially hollow wall. This construction is obtained by placing a slightly lesser amount of filler inthe open outer shell Il), inserting the closed inner shell 20, closing the outer shell with the cap I4 and then, while the filler is still molten, inverting the package so that filler will flow into the space between the cap III and the inner shell 20. To prevent the inner shell 20 from falling into said space, it is preferable to provide the cap 24 with a spacer 21, .as shown in Fig. 3. To prevent the filler from freezing or solidifying as the package is inverted, so that flow of the filler into the space between the caps 24 and I4 would be prevented, it is particularly desirable that the contents of the shell 20 be heated. By repeated inversions of the package as the filler cools, a hollow wall container, in which boththe inner surface of the outer shell I0 and the outer surface of the inner shell 20 are impregnated and hermetically sealed, will be obtained. In most instances, flns or flutes of filler will extend between the shells, thereby strengthening the walls of the package. g

From the foregoing, it should be apparent that containers made according to this invention may be modified as to the shape and structure of the inner and outer shells, the closures therefor, and the composition of the filler as the requirements of specific packages will dictate to those skilled in the art. It is to be understood, therefore, that this invention is not to be considered to be limited to the specific embodiments disclosed, either in whole or in part, but by the following claims.

What is claimed is:

l. A method of rendering a container of fibrous material substantially impervious and of increasing the rigidity of said container comprising the steps of placing in an outer shell of fibrous stock a quantity of liquid filler which is normally substantially solid, inserting an inner shell of fibrous stock in said outer shell while said filler is liquid to extrude said filler between the walls of said shells, and then allowing said filler to solidify.

2. A method of rendering a container of fibrous material substantially impervious and of increasing the rigidity of said container comprising the steps of partly filling an open outer shell of fibrous stock with a molten filler which is normally substantially solid at atmospheric temperatures, inserting a closed inner shell of fibrous stock in said outer shell while said filler is molten to extrude said filler between the walls of said vshells and to impregnate the inner surface of said outer shell and the outer surface of said inner shell at least partly with said filler, and maintaining said inner shell within and spaced from said outer shell while said filler is allowed to cool and solidify.

3. The method of sealing and creating a vacuum within a container of fibrous stock comprising thev steps of lling a quantity of moltenfiller, which is normally solid and substantially impermeable to gases, in ari open outer shell, placing Y a closed inner shell, of which at least a portion is comprised of "porous fibrous stock, within said outer shell, the quantity of filler in said outer shell being sufficient to permit ,said inner shell to be submerged in said filler andthe fibrous stock of said inner shell being suiiiciently porous to permit gases enclosed in said inner shell to escape through said fibrous stock, and then al lowing said filler to solidify While said inner shell is submerged.

4. The method of sealing and creating a vacuum Within a container of brous stock as deiined in claim 3 including t-he stepsof heating the contents of said inner shell to a temperature above normal atmospheric temperatures prior to inserting said inner shell in said outer shell, and inserting said inner shell in said outer shell while said contents are heated.

5. The method of making a container of fibrous stock substantially impervious to liquids and gases comprising the step of partly lling an open outer shell of fibrous stock with a quantity of molten ller and impregnating agent which is normally substantially solid and impervious to the liquids and gases to which it is desired to render the container impervious, inserting a closed inner shell of brous stock in the outer shell While said ller and impregnating agent is still molten to extrude said filler and impregnating agent between the Walls of said shell, al lowing said ller and impregnating agent to cool and solidify, pouring an additiona1 quantity of ller and impregnating agent in said outer shell to iill said outer shell completely with said ller and impregnating agent, and then closing said outer shell.

6. The method of making a container of fibrous stock substantially impervious to liquids and gases as dened in claim 5 including the steps of heating the contents of said inner shell prior to inserting said inner shell in said outer shell, and maintaining said inner shell submerged in said filler and impregnating agentand spaced from said outer shell while said liller and impregnating agent is allowed to cool and solidify.

7. The method of making a double Wall container of fibrous stock Whichis impervious to liquids and gases comprising the steps of partls7 lling an open outer shell of brous stock with a molten ller and impregnating agent which is normally solid at atmospheric temperatures, inserting a closed inner shell of brous stock in said outer shell while said ller and impregnating agent is molten to extrude said filler and impregnating agent between the Walls of said shells and to impregnate, at least partly, a portion of the surfaces of the Walls of said shells, closing said outer shell, and then inverting said shells while said ller and impregnating agent is still molten but While said shells are cooling to impregnate, at least partly, the remainder of the inner surface of the Walls of said outer shell and the outer surface of the walls of said inner shell.

8. The method of making a double Wall container of iibrous stock as defined in claim 7 including the steps of heating the contents of said inner shell prior to inserting said inner shell in said outer shell, and maintaining said inner shell spaced from said outer shell while said i-lller and impregnating agent is solidifying and impregnating the Walls of said shells.

FRANK GILBERT, JR. 

